greensand vs sandstone

greensand and sandstone both are nouns.

Word	Noun	Adjective	Verb	Adverb
greensand	Yes	No	No	No
sandstone	Yes	No	No	No

As nouns, sandstone is a hypernym of greensand; that is, sandstone is a word with a broader meaning than greensand:

greensand: an olive-green sandstone containing glauconite
sandstone: a sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)

greensand (noun)	sandstone (noun)
an olive-green sandstone containing glauconite	a sedimentary rock consisting of sand consolidated with some cement (clay or quartz etc.)